1. Field of the Invention
The present invention relates to a backpack type power working machine such as a bush cutter, a hedge trimmer and the like, and more specifically, to a backpack type power working machine arranged such that an internal combustion engine unit, for example, a small air-cooled two-cycle gasoline engine, is supported on a backpack frame so that it turns about a longitudinal axis.
2. Description of the Related Art
Operators who carry a backpack frame on their back can conveniently use this type of backpack type power working machines by turning an internal combustion engine unit when necessary and drawing out a working tool, which extends from the internal combustion engine unit, in a direction where they can easily execute a job. According to the backpack type power working machines, a position to which the working tool is drawn out can be suitably changed to the right side or to the left side of the body of the operators so that the operators can easily execute the job depending upon whether the operators are a right-handed person or a left handed-person or in correspondence to the change of various working environments such as an inclination and the like of a working field.
In the backpack type power working machines arranged as described above, if the internal combustion engine unit can be unlimited turned with respect to the backpack frame, there may be caused a trouble that the working tool comes into strong contact with the longitudinal portion of the backpack frame and with the operator when the position to which the working tool is drawn out is changed or while the operator executes the job, to thereby damage the longitudinal portion and injure the operator. To prevent the working tool from coming in contact with the backpack frame and the operator, a first stopper is conventionally fixed to the backpack frame to restrict the turning angle of the internal combustion engine unit within a predetermined allowable angle range.
Further, there is a danger that the exhaust gas port of an exhaust gas muffler constituting the internal combustion engine unit is directed to the operator (backing plate side) and the operator is exposed to the hot exhaust gas from the internal combustion engine unit even within the allowable turning angle range, depending upon a direction of the internal combustion engine unit. To prevent the exhaust gas from being directed to the operator, a second stopper is conventionally detachably disposed to the backpack frame to restrict, for example, the turning angle of the internal combustion engine unit within a safe turning range in the allowable turning angle range. Thus, the operator executes the job by mounting or dismounting the second stopper when necessary.
However, there is a problem that since the job must be interrupted when the second stopper is mounted or dismounted, a working efficiency is deteriorated as well as mounting and dismounting of the second stopper is troublesome.